1. Field of the Invention
The invention relates to a reactor and, more particularly, to a planar reactor capable of reducing coil loss effectively.
2. Description of the Related Art
In electronic equipment, it is necessary to use a magnetic component to achieve filtering or energy storage for circuit design. For example, a reactor is applied to a variable-frequency drive or an inverter. To enhance operating efficiency or rotational speed (torque) of a motor, it tends to use the variable-frequency drive or the inverter to drive the motor. As technology advances and develops, the existing products are requested to be light, thin, short and small. Accordingly, a reactor with large current design, which is applied to the variable-frequency drive or the inverter, also has to be flatted. However, after flatting the reactor with a core, the thickness of upper/lower board of the reactor will decrease. Under magnetic flux conservation scheme, the width of the pillar of the core will also decrease. To satisfy the requirement of saturation current for the core, the pillar of the core must have a specific cross-sectional area. Therefore, the length of the pillar of the core will increase, such that the ratio of the length to the width of the pillar of the core will increase. If the ratio of the length to the width of the pillar of the core increases, the winding circumference of the coil will also increase, such that the cost and loss of the coil will increase correspondingly.